Amtrak officials announced Monday that the three-year project to replace the railroad bridge spanning the Niantic River is 50 percent complete.

"We're on schedule," Peter Finch, the project manager, said.

The project includes a track realignment and the restoration of the Niantic Bay boardwalk, which was partially dismantled to make way for the new track.

Finch led local leaders, including East Lyme First Selectman Paul Formica, Waterford First Selectman Dan Steward and a staff member from U.S. Rep. Joe Courtney's office on a tour of the construction site Monday.

The $125 million project, funded with both federal stimulus funds and with Amtrak's capital budget, began in April 2010 and is expected to be complete in May 2013.

The 50 passenger trains that cross the Niantic River every day are scheduled to start using the new bridge next summer. Demolition of the old bridge will begin in the fall of 2012.

Portions of the bridge are under construction in factories in Alabama, Illinois and New Hampshire and will be assembled at the work site next year.

In the coming months, crews will install an electric submarine cable crossing, complete the bridge abutments and begin casting a new sea wall.

The new span, like its 104-year-old predecessor, will be a bascule bridge, similar in function to the famous Mystic River Highway Bridge in Mystic but on a larger scale.

"It will pivot on a giant bearing," Finch said.

Crews have nearly completed the pier for the bascule bridge and the "rest" pier on the Waterford side of the span, where the bridge rests when it's closed.

Finch said the new bridge, located 58 feet south of the existing bridge, will be 15.5 feet off the water, giving it nearly 5 feet more clearance than the current span.

Once the project is complete, the channel underneath the bridge will expand from 45 to 100 feet. Crews plan to install new safety markers for boaters on the piers.

The U.S. Coast Guard announced earlier this year that the channel will remain open and unobstructed during the summer boating season. There could be channel closures in the fall and winter.

Amtrak is also building a jetty, similar to the one at Hole-in-the-Wall Beach, near the bridge that will deposit sand on the shoreline, thereby creating a new beach.

Later Monday, Amtrak held an informational session for the public at East Lyme Town Hall that was attended mostly by maritime business owners on both banks of the Niantic River. John Wadsworth, who owns Mago Point Marina in Waterford, said the relationship between Amtrak, the contractors and businesses has been good "for the most part."

"Once this is done, it will be good for everyone," Wadsworth said.

Formica said Monday he has been impressed with quality of the lines of communication between Amtrak and East Lyme.

"It was an initial worry," Formica said. "But the communication really has been exceptional."

Steward said that there have been complaints from neighbors about the noise associated with the project.

"Amtrak has tried to make this palatable to people," Steward said. "It's a big project."

s.chupaska@theday.com

Waterford First Selectman Dan Steward, left, and East Lyme First Selectman Paul Formica watch workers as they get a tour of the Niantic railroad bridge replacement project Monday.